[arch-projects] Fwd: [initscripts] [PATCH] Setting Locale: fix status reporting FAIL erroneously

[Kurt J. Bosch]

Dave Reisner, 2011-06-26 19:14:
> On Sun, Jun 26, 2011 at 06:59:09PM +0200, Kurt J. Bosch wrote:
>> Tom Gundersen, 2011-06-26 17:00:
>>> On Sun, Jun 26, 2011 at 4:06 PM, Dave Reisner<d at falconindy.com>   wrote:
>>>> On Sun, Jun 26, 2011 at 03:12:24PM +0200, Kurt J. Bosch wrote:
>>>>> Tom Gundersen, 2011-06-26 13:51:
>>>>>> On Sun, Jun 26, 2011 at 1:03 PM, Kurt J. Bosch
>>>>>> <kjb-temp-2009 at alpenjodel.de>     wrote:
>>>>>>> The following test case (run in a terminal)
>>>>>>>
>>>>>>> #!/bin/bash
>>>>>>>
>>>>>>> # custom override example
>>>>>>> stat_busy() {
>>>>>>>         if (( PUSH_MSG )); then
>>>>>>>                 # This triggers the error in "$@" below
>>>>>>>                 # actual code was:
>>>>>>>                 # echo set message "$1">     "$spl_fifo"&
>>>>>>>                 :&
>>>>>>>         fi
>>>>>>>         echo "$1" BUSY
>>>>>>> }
>>>>>>>
>>>>>>> status() {
>>>>>>>         stat_busy "$1"
>>>>>>>         shift
>>>>>>>         "$@"
>>>>>>>         local retval=$?
>>>>>>>         (( retval == 0 ))&&     echo DONE || echo FAIL "($retval)"
>>>>>>> }
>>>>>>>
>>>>>>> PUSH_MSG=0 status "test #0" cat<(echo foo)
>>>>>>> PUSH_MSG=1 status "test #1" cat<(echo foo)
>>>>>>
>>>>>> [...]
>>>>>>
>>>>>>> CCing Tom Gundersen.
>>>>>>
>>>>>> Thanks.
>>>>>>
>>>>>> I have not figured it out, but here is a more minimal test:
>>>>>>
>>>>>>
>>>>>> #!/bin/bash
>>>>>>
>>>>>>
>>>>>> test_one() {
>>>>>>         :&
>>>>>>         "$@"
>>>>>> }
>>>>>>
>>>>>> test_two() {
>>>>>>         :
>>>>>>         "$@"
>>>>>> }
>>>>>>
>>>>>> # working
>>>>>> test_one eval 'cat<(echo foo)'
>>>>>> test_two cat<(echo foo)
>>>>>>
>>>>>> #not working
>>>>>> test_one cat<(echo foo)
>>>>>
>>>>> Confirmed.
>>>>>
>>>>> --
>>>>> Kurt
>>>>
>>>> Now I see it (at least in Tom's example). It's expected behavior. You're
>>>> only allowed to read the file descriptor created by a PE once. However,
>>>> because file descriptors are inherited by subshells, when the subshell
>>>> ends, the file descriptor is closed and it goes away. Look at what
>>>> happens when you modify the script slightly:
>>>>
>>>> -------------------
>>>>
>>>> #!/bin/bash
>>>>
>>>> test_one() {
>>>>   ls /dev/fd/
>>>>   :&
>>>>   ls /dev/fd/
>>>>   "$@"
>>>> }
>>>>
>>>> test_one cat<(echo foo)
>>>>
>>>> -------------------
>>>>
>>>> And then run it with debug output....
>>>>
>>>> +foo[11]: test_one cat /dev/fd/63
>>>> +foo[4]: ls /dev/fd/
>>>> ++foo[11]: echo foo
>>>> 0  1  2  3  63
>>>> +foo[6]: ls /dev/fd/
>>>> +foo[5]: :
>>>> 0  1  2  3
>>>> +foo[7]: cat /dev/fd/63
>>>> cat: /dev/fd/63: No such file or directory
>>>>
>>>> The subshell inherits the descriptor and closes it on exit, destroying
>>>> it for the parent. The eval "works" because the FD for the process
>>>> substitution isn't created until _after_ the subshell.
>>>>
>>>> Can we _not_ do this? Our old solution didn't require voodoo like this,
>>>> and it worked just fine (albeit a few more SLOC). Not everything needs
>>>> to be a one line operation. Perhaps we could just write a simple
>>>> function to take care of all these 1 line files that we write to:
>>>>
>>>> write_oneline_file() {
>>>>   local file=$1 line=$2 mode=$3
>>>>
>>>>   printf '%s\n' "$line">"$file"
>>>>   [[ $mode ]]&&   chmod "$mode" "$file"
>>>> }
>>>>
>>>> Which satisfies both parties, as it appears to be a one liner in
>>>> execution, but it's actually sane on the back end.
>>>
>>> Thanks for your explanation Dave. I like your solution, should make
>>> things more readable.
>>>
>>> -t
>>>
>>> [sorry for duplicate, forgot CC]
>>
>> I would like to go a bit further with this:
>> a) Drop the 'oneline' and the '\n' to be able to use it for any
>> number of lines including zero.
>> b) Allow more options like owner, group, create parent directory.
>>
>> Maybe like so:
>>
>> install_file() {
>>    local file=$1 content=$2 # remaining args go to install directly
>>    shift 2
>>    install -T "$@"<(printf '%s' "$content") "$file"
>> }
>>
>> Then these candidates:
>>
>>   --- rc.sysinit ---
>> 221: install -Tm 0664 -o root -g utmp<(:) /var/run/utmp
>> 264: install -Tm 0600<( dmesg ) /var/log/dmesg.log
>> 266: install -Tm 0644<( dmesg ) /var/log/dmesg.log
>>   --- rc.shutdown ---
>> 24:  install -TDm 0600<(:) $RANDOM_SEED
>>
>> could be turned into:
>>
>>   --- rc.sysinit ---
>> 221: install_file /var/run/utmp "" -m 0664 -o root -g utmp
>> 264: install_file /var/log/dmesg.log "$( dmesg )" -m 0600
>> 266: install_file /var/log/dmesg.log "$( dmesg )" -m 0644
>>   --- rc.shutdown ---
>> 24:  install_file $RANDOM_SEED "" -m 0600 -D
>>
>> There is only one small drawback - we would need to add the trailing
>> newline explicitly if wanted:
>>
>>   --- rc.sysinit ---
>> 232: install_file /etc/profile.d/locale.sh "export
>> LANG=$LOCALE"$'\n' -m 0755
>>
>> --
>> Kurt
>
> ACK. I'm good with this. The shell doesn't complain when there's no
> trailing newline on the locale file. Is it really necessary? Do we have
> a [CZK]SH user who can weigh in?
>
> d
>
Don't know, but we add one more line in functions:

504-	elif [[ $CONSOLEMAP ]]; then
505:		cat <<"EOF" >>/etc/profile.d/locale.sh
506-if [ "$CONSOLE" = "" -a "$TERM" = "linux" -a -t 1 ]; then printf 
"\033(K"; fi
507-EOF

-- 
Kurt